package cn.haoxsf.app.common.util;

import java.text.DecimalFormat;

/**
 * Ele
 * 两点计算工具类
 */
public class DistanceCalculationUtils {

    private static double EARTH_RADIUS = 6378.137;

    private static double rad(double d) {
        return d * Math.PI / 180.0;
    }

    /**
     * 通过经纬度获取距离(单位：米)
     *
     * @param lat1
     * @param lng1
     * @param lat2
     * @param lng2
     * @return 距离
     */
    public static String getDistance(double lat1, double lng1, double lat2,
                                     double lng2) {
        double radLat1 = rad(lat1);
        double radLat2 = rad(lat2);
        double a = radLat1 - radLat2;
        double b = rad(lng1) - rad(lng2);
        double s = 2 * Math.asin(Math.sqrt(Math.pow(Math.sin(a / 2), 2)
                + Math.cos(radLat1) * Math.cos(radLat2)
                * Math.pow(Math.sin(b / 2), 2)));
        s = s * EARTH_RADIUS;
        s = Math.round(s * 10000d) / 10000d;
        s = s * 1000;
        return getDistance(s);
    }

    /**
     * 自动转换公里&米
     * @param distance
     * @return
     */
    private static String getDistance(Double distance) {
        int format = Integer.parseInt(new DecimalFormat("0").format(distance));
        if (distance >= 1000) {
//            nearbyList.put("distance",format/1000+"公里");
            return format / 1000 + "公里";
        } else if (distance < 1000) {
//            nearbyList.put("distance",format+"米");
            return format + "米";
        } else {
            return "距离错误";
        }
    }
}
